a) Field of the Invention
The invention is directed to a method for monitoring a control system comprising a plurality of control units, preferably for an optical measurement device or observation device.
b) Description of the Related Art
In the case of complex measurement devices or observation devices, it is known to carry out the various device settings depending on the measurement or observation task at hand by means of actuating or adjusting units which are driven by electric motor. For example, commands are entered via a computer keyboard, evaluated in a computer serving as control station, and conveyed to the respective adjusting units. In high-quality microscope systems, for example, this relates to the adjustment of revolving lens turrets or objective turrets, field diaphragms and aperture stops, reflector turrets, variable condensers, cross-slide stages for X- and Y-displacement vertical to the microscope beam path, and for displacement in the Z-coordinate. Electronically controllable adjusting movements in the illumination configuration are also common.
In order to be able to use all possible device configurations without restriction, it has proven successful to actuate the adjusting units through control circuits, wherein a control circuit together with an associated adjusting unit generally forms a separate control unit. All control units and the control station form a control system and are linked via data lines for purposes of transmitting information.
The transmission of information is often carried out between the control station, which functions as main computer or master, and the control units based on the master-slave principle, as it is called, i.e., commands are sent from the control station to the slaves. The slaves execute these commands and, based on the principle of “polling”, as it is called, transmit the status achieved in the course of executing the command, e.g., the adjusting position that has been reached, in response to inquiries which are directed in timed intervals from the control stations to the slaves. In this way, the control station gathers the status information of all slaves and accordingly obtains an illustration of the situation within the entire control system or in the device.
A disadvantage in this previously known procedure consists in the fact that the transmission of commands to the slave, the initiation of adjusting processes and the inquiries and reports relating to the execution of the command takes a relatively long time. For example, when initiating an adjusting process lasting one to two seconds, the control station is occupied during this time with polling the status until, finally, it is reported that the desired adjusting position has been achieved or the adjusting process has been successfully concluded.
Since the time of the conclusion of an adjusting process must also often be detected by the control station, the communication between the control station and slave takes place for the entire duration of the adjusting process until the inquiry results in a “ready” state and the corresponding time can be recorded.
For example, when the report concerning the conclusion of the adjusting process for an objective turret has been received, the next process, e.g., changing a field diaphragm, can be initiated. But the control station is then occupied again until this process is also terminated, and only then can the next adjusting process be initiated.
The greater the quantity of communication units associated with a control system of this type and connected with the control station, the greater the burden on the control station and the information paths. This procedure of continuous inquiry and response between the control station and slaves has accordingly proven to be disadvantageous with respect to the desired effective utilization of existing capacities of the control station and communications paths.